1. Field of the Invention
The present invention relates to AC gas discharge display and memory panels. More particularly, the present invention relates to a blue color AC gas discharge display and memory panel exhibiting high luminous efficiency.
2. Description of the Prior Art
One of the limitations of the conventional AC gas discharge display panel, typically utilizing neon/argon as the luminous gas mixture, resides in the fact that such gas produces a reddish-orange color. The reddish-orange color is objectionable for a variety of human-factors reasons. For example, under certain ambient light conditions, such as use in sun light, the reddish-orange color is difficult to see. The use of gas mixtures, other than those with a dominant percentage of neon, to give direct emission of alternative colors has historically been found to be not satisfactory, since the luminous efficiencies achieved from such alternative gas mixtures are too low. Accordingly, as heretofore obtained in the art, the requirement for good luminous efficiencies necessitated the use of gas mixtures having a dominant percentage of neon and an acceptance of the reddish-orange color obtained therefrom.
Alternative color capability in gas discharge display panels has been pursued by an indirect method. Basically, this indirect method utilizes photosensitive phosphors in the active discharge region, which phosphors are stimulated by uv emission from a suitable gas mixture. Various arrangements have been implemented in the prior art utilizing this principle. However, since the principle utilizes phosphors stimulated by emission from the gas, additional and somewhat complex fabrication is required, and brightness and efficiencies are lost. Typical of the prior art gas discharge display panel utilizing this approach is that described by Brown et al in an article entitled "A Multicolor Gas-Discharge Display Panel," appearing in the proceedings of the S.I.D., Vol. 13, First Quarter 1972.
The use of Ar-Hg gas mixtures has heretofore been used in the lamp industry. The conventional fluorescent lamp utilizes such a mixture. However, the fluorescent lamp uses a low Ar pressure of typically 2.5 Torr with an optimum Hg vapor pressure of 6-10m Torr obtained by running the tube with a wall temperature of approximately 40.degree. C. Thus, in such an arrangement, the Hg vapor pressure is always greater than approximately 0.25% of the bulk gas pressure and the discharge conditions are optimized for electron excitation of uv resonance radiation of Hg. As will be more fully explained, the present invention uses room-temperature Hg in at least 300 Torr of Ar.
It has also been known in the prior art to use high-pressure Hg lamp mixtures. Typically, such lamps use 25 Torr of Ar and well over one atmosphere of Hg vapor pressure during operation. Also known in the prior art are high-pressure Hg-vapor lamps typified by U.S. Pat. No. 2,240,353 to Schnetzler, and high-pressure Ar lamps typified by U.S. Pat. No. 2,241,968 to Suits. Typical of the high-pressure Hg lamp mixture (with Ar) is that described in U.S. Pat. No. 2,761,086 to Noel et al.
The introduction of Hg vapor into DC gas discharge display panels is also known in the art. However, the Hg vapor is introduced into these cold cathode-type display devices for purposes of inhibiting sputtering. Typical of such prior art approaches is that described by Fehnel in U.S. Pat. No. 3,828,218 and Kupsky in U.S. Pat. No. 3,580,654.